Climate experts have started to worry that the ice cap is disappearing in ways that computer models had not predicted.

By all accounts, the glaciers of Greenland are melting twice as fast as they were five years ago, even as the ice sheets of Antarctica — the world's largest reservoir of fresh water — also are shrinking, researchers at NASA's Jet Propulsion Laboratory and the University of Kansas reported in February.

One of the common wingnut "rebuttals" of An Inconvenient Truth is to say that Gore's "predictions" (which he doesn't make) about flooding resulting from glaciers melting won't happen for centuries, or millenia. The problem is that - as we find more and more research like this - it's clear we are no longer on a linear path. Rather, we're finding positive-feedback all over the place, especially at the poles where warming is happening fastest.

As just one (of many) examples of positive feedback, it seems that the last time the Greenland Ice Sheet melted, the sea level rose by a much higher amount than can be explained by Greenland alone. The theory is that the rise in sea level from Arctic ice triggered a partial collapse of the West Antarctic Ice Sheet.

As Kevin Drum notes, "So in a way, the skeptics have turned out to be right: the computer models aren't as reliable as we thought. They're too optimistic." Meanwhile, North America (and I include my Canadian countrymen in this indictment) has wasted almost 20 years claiming that the "science wasn't clear."

Someday, I hope we build a monument (on high ground) and chisel the names of every prominent climate-change "skeptic" on it, to shame them for all eternity. But for that plan to work, they would need to have shame in the first place.